Not counting the Steam Deck, since KDE isn’t actually turned on while you’re running games.
Normally I’m a Gnome guy, but I’m building a tiny low power portable computer and wanting to keep resource utilization low, so I’m investigating other options.
xfce! I don’t Hardcore Game or anything but I find it easy to customize without being overwhelming or clunky at all, so there’s that.
Xfce might be the choice here, since most of benefits of Wayland won’t really apply to this machine (from an end user perspective) and it is relatively lightweight.